Mild to moderate hypertension

Severe hypertension

Angina prophylaxis

Dosage recommendations by manufacturer may vary.

A slight alteration of the pharmacokinetics of nifedipine may be seen in the elderly therefore caution advised. Lower maintenance doses of nifedipine may be required compared to younger patients.

Not licensed for use in children under 18 years.

Administration

For oral administration.
To be swallowed whole with water at the same time each day, either with or without food. Under no circumstances are they to be broken up, bitten or chewed.

Contraindications

Cardiogenic shock
Severe aortic stenosis
Unstable angina
During or within one month of a myocardial infarction
History of gastrointestinal obstruction
Presence or history of oesophageal obstruction
Inflammatory bowel disease
Crohn's disease
Presence or history of decreased gastrointestinal tract lumen diameter
Not to be administered to patients with Kock pouch (ileostomy after proctocolectomy)
Galactosaemia
Children under 18 years

Precautions and Warnings

Prescribe by brand only to ensure consistent bioavailability.

Hepatic impairment (see Dosage - Hepatic Impairment ).

Acute porphyria (see Porphyria ).

Use with caution in patients with cardiac failure, poor cardiac reserve or significantly impaired left ventricular function. Deterioration of heart failure has been observed.

The safety of nifedipine in malignant hypertension has not been established.
In dialysis patients with malignant hypertension and irreversible renal failure with hypovolaemia, a marked decrease in blood pressure can occur.

Cardiac ischaemic pain has been reported in a small proportion of patients shortly after initiating nifedipine therapy. Although a 'steal' effect has not been demonstrated, withdraw treatment if ischaemic pain occurs or existing pain worsens shortly after commencing therapy. Use of nifedipine can lead to increased complaints of angina, if this occurs the physician should be alerted and treatment ceased.

Hypotensive patients should be treated with caution as there is a risk of further reduction in blood pressure. Extreme caution should be taken in patients with systolic pressure less than 90mmHg. Nifedipine may be used in combination therapy with beta blocking agents or other antihypertensive agents. However the potential for an additive effect must be borne in mind as postural hypotension and/or cardiac failure could result.
Transient blindness may occur following an excessive fall in blood pressure.

Diabetic patients may require adjustment of their control. Use with caution in patients with possible hyperglycaemia.

Will not prevent rebound effects of cessation of other antihypertensives therefore their withdrawal should be gradual. Sudden withdrawal may be associated with angina.

Hypersensitivity-type jaundice has been reported.
Grapefruit products increase the bioavailability of dihydropyridine calcium channel blockers. Patients should be advised to avoid grapefruit and grapefruit juice.

Pregnancy (see Pregnancy ).
Breastfeeding (see Lactation ).

May inhibit labour.

In vitro fertilisation treatment: calcium antagonists may adversely affect sperm function and should be considered as a possible cause in men repeatedly unsuccessful in fathering a child via in vitro fertilisation and where no other explanation can be found.

Elderly (see Dosage - Elderly ).

A false positive effect may be seen when performing a barium contrast x-ray.

Nifedipine may increase the spectrophotometric values of urinary vanillylmandelic acid falsely. HPLC measurements, however, are not affected.

In some formulations, the outer membrane of the tablet is not digested and therefore what appears to be a complete tablet may be seen in the toilet or stools. In very rare cases bezoars can occur and may require surgical intervention.

The ability to drive or operate machinery may be affected by side effects of nifedipine such as transient blindness, dizziness and lethargy.

Advise patients to moderate alcohol intake during nifedipine therapy as it can increase the likelihood of side effects.

Not suitable for secondary prevention of myocardial infarction.

Not suitable for acute attacks of angina or for patients who have had ischaemic pain following previous administration.

Advise patient to avoid taking St. John's Wort.

Some formulations contain lactose, use with caution in patients with lactose intolerance or glucose-galactose malabsorption syndrome.

Use in Porphyria

Many nifedipine brand manufacturers consider nifedipine as being porphyrinogenic. Calcium channel blockers are considered unsafe however nifedipine may be used with caution. The Norwegian Porphyria Centre (NAPOS) classifies nifedipine as being 'probably not porphrinogenic'.

Pregnancy and Lactation

Pregnancy

Use with caution in pregnancy and in women who are planning pregnancy. There is limited information to support the use of calcium blockers in human pregnancy. Studies in sheep with IV infusions of nifedipine indicate a progressive decrease in mean maternal arterial blood pressure. The hypotensive effect resulted in a decrease in uterine blood flow and foetal arterial oxygen content. Reproduction studies in rats and rabbits have shown a teratogenic effect resulting in digital anomalies. Other toxicities were noted in embryos and foetuses of mice, rats and rabbits at doses 3.5-42 times the maximum recommended human dose; these include stunted foetuses, rib deformities, cleft palate, embryo and foetal deaths as well as prolonged pregnancy and decreased neonatal survival. Nifedipine administered intravenously in pregnant rhesus monkeys has been associated with foetal hypoxaemia and acidosis (Briggs, 2011).

Lactation

Use with caution during breastfeeding

Nifedipine is excreted in breast milk in small amounts, which are considered too small to be harmful. No adverse effects have been reported among a limited number of infants exposed to nifedipine in breast milk.

Nifedipine has also been used to treat painful nipple vasospasm in nursing mothers.